The proliferation of biological weapons and the prospect of terrorism have significantly heightened the need to develop more effective and practical measures for monitoring and detecting biological agents dispersible from such weapons. Such protective measures would be effective for alerting civilian emergency and military personnel of an impending attack and enable those under attack to take necessary defensive actions.
One class of biological agents of concern includes staphylococcal enterotoxins. Staphylococcal enterotoxins are superantigenic protein toxins produced by the bacteria Staphylococcus aureus (S. aureus). They are generally made up of low molecular weight single-chain proteins (23-29 kDa) subdivided into several serotypes including A, B, C1, C2, C3, D, E, G and H, and which are encoded by five genes which share 50% to 85% homology.
Staphylococcal enterotoxins are the most frequent cause of food poisoning typically resulting in diarrhea and vomiting. In more serious cases, they can trigger toxic shock and immunosuppression. Although high-dose exposures can cause fatalities, it is the incapacitating capability of inhalational exposure on the battlefield or in a populated area that are of most concern in the context of biological defense. In particular, one staphylocbccal enterotoxin that can be readily weaponized is staphylococcal enterotoxin A (SEA). Staphyloccocal enterotoxin A, a 27 kDa monomeric protein, is considered to be one of the more potent of the staphylococcal enterotoxin serotypes. Current methods for detecting staphylococcal enterotoxin A are typically time-consuming, labor intensive and unreliable.
Accordingly, there is a need for an assay and a method of detecting the presence of staphylococcal enterotoxin A gene that is relatively fast, accurate and cost effective to implement. There is a further need to develop methods with enhanced sensitivity capable of detecting the presence of genes or nucleic acids encoding staphylococcal enterotoxin A even at low concentration levels. It would be also desirable to develop novel nucleic acid probes and primers useful for detecting nucleic acids, which encode or express staphylococcal enterotoxin A for determining the presence of the toxin itself in a sample.